CHAPTER VIlJ.. 



OF THE modifying' AGENTS OF NUTRITION. 



Vabious influences modify the nutritive movement, more or 

 less, for better or worse. These influences dwell either in the 

 organism itself, or outside it. 



A. It might be said that nutrition is the object of life, if life 

 has an object ; but it has none, since it is simply the result of 

 a fortuitous concurrence of cosmical^ geolo^cal, climacteric, and 

 even orological facts. It has not always existed on the surface 

 of our little planet. It will be extinguished there one day. 

 But, if we cannot say that nutrition is the object of life, we 

 are justified in saying that it is the basis thereof. A given 

 organism lasts, prospers, develops and reproduces itself the 

 more surely the better nourished it is, and it is the better 

 nourished the better organised it is, that is to say, in more 

 complete harmony with the exterior medium. Also, as we shall 

 see hereafter, the various organic systems of every complex 

 animal are regulated with regard to nutrition. The result of 

 the special functionment of each of them is to render nutrition 

 possible and easy. Here is a series of organic harmonies, of 

 which we shall give an exposition farther on. We shall see 

 that there are systems of organs adapted, some to render the 

 aliments absorbable, others to convey the nutritive substances to 

 the tissues ; whilst certain others have the function of ventilating 

 to some extent the anatomical elements, furnishing them with 

 oxygen, and relieving them of their carbonic acid. Finally, 



